In order to explain the increased resistance to shock which develops in rats after repeated injections of endotoxine and after administration of depot catecholamines, the vasoconstrictory effect of catecholamines will be studied in isolated rat's liver in the liver- perfusion apparatus. Perfusion (portal) pressure will be measured using a pressure transducer. Simultaneously, different functions of the liver will be measured as e.g. catabolism of catecholamines and resistance of the liver lysosomes to anoxia.